Scrapbook - buy the kind with plastic sleeves and have each person or each family do a page. We did this for Grandma's 90th and it was fabulous. Everyone bought their own background papers and selected photos and little embellishments (stickers, etc.) that went along that theme. Everyone wrote a letter about what they appreciate about her - some were serious & heartfelt, some were amusing, some a combination. The letters were typed and then put on the page with other items (photos, ticket stubs, captions, etc.) Then when we got together, we laid everything out while someone else distracted her, and we assembled the book. We had some scrapbooking supplies and made some captions and other additions to make it hang together. We gave it to her at the party. She has continued to look over that for the past few years and it has really helped her with feeling appreciated and that she's had a great influence on so many of us. We left some blank pages at the back so we could add photos from the celebration. You could all take pictures and then each family could send her an extra page after the reunion.
You could get a blank book and create 60 memories or 60 comments. Everyone could add their own. It helps if you don't overlap too much - so if one person mentions her great apple pies or homemade Christmas gifts, the next person should have some different ones to mention even if he/she has the same memory.
If she's a cook, collect her best recipes and create a cookbook for all the family members. Same thing for any other skill or special interest she has.